There is a limit to what can be seen with visible light. Light has a wavelength (length), and those shorter than the wavelength of light can not be seen by the eye. There are limits of optical microscope / microscope there.
Therefore, an electron microscope using an electron beam (electron beam) whose wavelength is shorter than visible light.
In the past, there were only 10 million yen or more for digital micrometer microscope. Right now, some digital micrometer were about 6 million yen.
There is a public test research institute called an industrial testing center in each province, and some institutions that can use the examination request and equipment of the digital micrometer microscope.